For Patients

Theo-24 (theophylline, anhydrous) is used to treat the symptoms of asthma, bronchitis and emphysema. It is a bronchodilator. Common side effects include mild nausea, loss of appetite, weight loss, restlessness, tremor, or insomnia, headache, lightheadedness, or dizziness.

Theo-24 is taken once daily, in doses ranging from 100 mg to 400 mg. Theo-24 may interact with carbamazepine, cimetidine, enoxacin, ephedrine or similar medications found in cold medicine or diet pills, erythromycin, fluvoxamine, propranolol, rifampin, St. John's wort, or thiabendazole. Tell your doctor all medications and supplements you use. During pregnancy, Theo-24 should be taken only if prescribed. It may be harmful to a fetus. This medication can pass into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding.

Our Theo-24 (theophylline, anhydrous) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Patient Information in Detail?

Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.

SIDE EFFECTS

Adverse reactions associated with theophylline are generally mild when peak
serum theophylline concentrations are < 20 mcg/ mL and mainly consist of
transient caffeine-like adverse effects such as nausea, vomiting, headache,
and insomnia. When peak serum theophylline concentrations exceed 20 mcg/mL,
however, theophylline produces a wide range of adverse reactions including persistent
vomiting, cardiac arrhythmias, and intractable seizures which can be lethal
(see OVERDOSAGE). The transient caffeine-like
adverse reactions occur in about 50% of patients when theophylline therapy is
initiated at doses higher than recommended initial doses (e.g., > 300 mg/day
in adults and > 12 mg/kg/day in children beyond 1 year of age). During the
initiation of theophylline therapy, caffeine-like adverse effects may transiently
alter patient behavior, especially in school age children, but this response
rarely persists. Initiation of theophylline therapy at a low dose with subsequent
slow titration to a predetermined age-related maximum dose will significantly
reduce the frequency of these transient adverse effects (see DOSAGE
AND ADMINISTRATION, Table V). In a small percentage of patients ( <
3% of children and < 10% of adults) the caffeine-like adverse effects persist
during maintenance therapy, even at peak serum theophylline concentrations within
the therapeutic range (i.e., 10-20 mcg/mL). Dosage reduction may alleviate the
caffeine-like adverse effects in these patients, however, persistent adverse
effects should result in a reevaluation of the need for continued theophylline
therapy and the potential therapeutic benefit of alternative treatment.

Other adverse reactions that have been reported at serum theophylline concentrations
< 20 mcg/mL include diarrhea, irritability, restlessness, fine skeletal muscle
tremors, and transient diuresis. In patients with hypoxia secondary to COPD,
multifocal atrial tachycardia and flutter have been reported at serum theophylline
concentrations ≥ 15 mcg/mL. There have been a few isolated reports of seizures
at serum theophylline concentrations < 20 mcg/mL in patients with an underlying
neurological disease or in elderly patients. The occurrence of seizures in elderly
patients with serum theophylline concentrations < 20 mcg/mL may be secondary
to decreased protein binding resulting in a larger proportion of the total serum
theophylline concentration in the pharmacologically active unbound form. The
clinical characteristics of the seizures reported in patients with serum theophylline
concentrations < 20 mcg/mL have generally been milder than seizures associated
with excessive serum theophylline concentrations resulting from an overdose
(i.e., they have generally been transient, often stopped without anticonvulsant
therapy, and did not result in neurological residua).

Table IV. Manifestations of theophylline toxicity.*

Percentage of patients reported with sign
or symptom

Acute Overdose
(Large Single Ingestion)

Chronic Overdosage
(Multiple Excessive Doses)

Sign/Symptom

Study 1
(n=157)

Study 2
(n=14)

Study 1
(n=92)

Study 2
(n=102)

Asymptomatic

NR**

0

NR**

6

Gastrointestinal

Vomiting

73

93

30

61

Abdominal pain

NR**

21

NR**

12

Diarrhea

NR**

0

NR**

14

Hematemesis

NR**

0

NR**

2

Metabolic/Other

Hypokalemia

85

79

44

43

Hyperglycemia

98

NR**

18

NR**

Acid/base disturbance

34

21

9

5

Rhabdomyolysis

NR**

7

NR**

0

Cardiovascular

Sinus tachycardia

100

86

100

62

Other supraventricular tachycardias

2

21

12

14

Ventricular premature beats

3

21

10

19

Atrial fibrillation or flutter

1

NR**

12

NR**

Multifocal atrial tachycardia

0

NR**

2

NR**

Ventricular arrhythmias with

hemodynamic instability

7

14

40

0

Hypotension/shock

NR**

21

NR**

8

Neurologic

Nervousness

NR**

64

NR**

21

Tremors

38

29

16

14

Disorientation

NR**

7

NR**

11

Seizures

5

14

14

5

Death

3

21

10

4

* These data are derived from two studies
in patients with serum theophylline concentrations > 30 mcg/mL. In
the first study (Study #1-Shanon, Ann Intern Med 1993;119:1161-67), data
were prospectively collected from 249 consecutive cases of theophylline
toxicity referred to a regional poison center for consultation. In the
second study (Study #2-Sessler, Am J Med 1990;88:567-76), data were retrospectively
collected from 116 cases with serum theophylline concentrations > 30
mcg/mL among 6000 blood samples obtained for measurement of serum theophylline
concentrations in three emergency departments. Differences in the incidence
of manifestations of theophylline toxicity between the two studies may
reflect sample selection as a result of study design (e.g., in Study #1,
48% of the patients had acute intoxications versus only 10% in Study #2)
and different methods of reporting results.
** NR =Not reported in a comparable manner.